At Seaford Bay, on the coast of Sussex, the sea had made considerable encroachment, so as to jeopardise much of the adjacent property, and also the defences and martello-tower in its vicinity. Large sums of money had been expended in the construction of wood groins and clay embankments, with only partial success; and as an effectual remedy, it was proposed to throw down by mining a portion of the chalk rock itself, in the direction of the tidal current, and thus cause it to accumulate the shingle and protect the land and contiguous property. The cliff was high, bold, and bare, and worn at the base into hollows and long perpendicular crevices by the lashing of the waves, which, at high water, rushed up its aged and craggy face. With the view to efficiency and economy, the Master-General approved of the operations being carried out by a detachment of sappers and miners; and accordingly two sergeants and forty-four rank and file of the fourth company left Portsmouth at the end of July under Lieutenant E. W. Ward, R.E., who, on arriving at Seaford, lost no time in commencing the interesting undertaking. Late in August, the party was increased by ten rank and file under Captain Craigie, to assist in completing the final arrangements, and to take the military duty consequent upon the anticipated explosion. The works were conducted under the direction of Colonel G. G. Lewis, R.E., with Captain E. C. Frome as his executive officer. In the face of the cliff, about thirty-five feet above high-water mark, a nearly horizontal gallery was cut a considerable distance into the chalk. The mouth of this gallery was approached by a ladder and platform, supported by scaffolding. Inside the opening a cave was formed for spare tools and materials, and another also was excavated at the end of the gallery for a similar purpose. At right angles from this gallery, extending fifty-five feet to the right and sixty-five to the left, were corresponding galleries, at the extremities of which were two chambers of about seven feet cube, containing 12,000 lbs. of powder each. Two wires, respectively in connexion with two of Grove’s batteries, completed the arrangements for exploding these charges simultaneously. The chambers of powder were about seventy feet from the face of the cliff, and were intended to drive out its under portions and roll them towards the sea. Upon the surface of the rock, eighty-four feet from its edge, were sunk five vertical shafts, at the bottom of which other chambers were excavated, containing, in three of them, each 600 lbs. of powder, to be fired simultaneously with the two great charges. The two other chambers were not loaded, from the non-arrival of a sufficient quantity of powder. The shaft chambers were connected by wires to a Smee’s battery, placed in a wooden shed erected about 180 feet from the edge of the cliff. The wires to convey the electric fluid to each chamber were covered with tape and varnished or tarred over. The